Air conditioner condenser assembly

Abstract

An improved method for assembly of a brazed condenser unit for use in an automobile air conditioning system is provided which significantly reduced the defective rate due to leaky internal joints within the condenser. A sufficiently viscous flux composition is applied to the internal features of the condenser during assembly. The flux composition is specifically applied to surfaces of the aluminum alloy header which is clad internally with the brazing alloy, so as to promote complete and consistent brazing of the internal tubes and components. The brazing flux composition of this invention consists of potassium fluoaluminate particles in a liquid carrier consisting of a polyhydric alcohol, e.g., propylene glycol, and minimal amounts of water. This flux composition has a sufficiently high viscosity so as to permit its easy, consistent deposition on the header surface without subsequent displacement during assembly and processing.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A method for assembly of a condenser suitable for use in an automotive air conditioner or other refrigeration unit, comprising: providing a pair of spaced headers formed from an aluminum alloy brazing stock material wherein said aluminum alloy brazing stock material comprises an aluminum alloy core layer clad on at least a first surface with an aluminum-silicon brazing alloy, each of said spaced headers having a corresponding plurality of perforations;   depositing a braze flux on at least said first surface of each of said headers, said braze flux being deposited between each of said plurality of perforations in an amount sufficient to deoxidize and wet a region adjacent said perforations during a subsequent brazing operation, said braze flux comprising about 40 to about 60 weight percent potassium fluoaluminate particles dispersed in a liquid carrier, said liquid carrier consisting essentially of, by weight, from about 90 percent to 100 percent of a water miscible polyhydric alcohol of two to four carbon atoms and up to about 10 percent water;   inserting a tube into each of said corresponding perforations within each of said headers so as to extend in hydraulic parallel between said headers, such that each of said first surfaces of said headers having said braze flux are oppositely disposed across said extended plurality of tubes; and   brazing said plurality of tubes within said perforations of said headers by sufficiently heating said aluminum-silicon brazing alloy and said braze flux such that said braze flux deoxidizes said aluminum alloy core layer and said aluminum-silicon brazing alloy at said perforations while also enhancing the flowability of said aluminum-silicon brazing alloy, thereby being effective to form leak-proof brazed joints at said perforations so as to produce a leak-proof condenser suitable for use in a refrigeration system.   
     
     
       2. A method for assembly of a condenser as recited in claim 1 wherein said aluminum-silicon brazing alloy employed for formation of said headers is characterized by an aluminum-silicon brazing alloy having a silicon content of about 6.8 to about 14 weight percent. 
     
     
       3. A method for assembly of a condenser as recited in claim 1 wherein said brazing step occurs at a temperature of about 1070° F. to about 1135° F. 
     
     
       4. A method for assembly of a condenser as recited in claim 1 further comprising the step, prior to said brazing step, of inserting high surface area, finned portions between each of said tubes. 
     
     
       5. A method for assembly of a condenser as recited in claim 1 further comprising the steps of attaching each of said spaced headers to a corresponding extruded aluminum alloy tank means so as to form a plurality of tanks and attaching a vapor inlet and a condensate outlet such that each of said tubes is in fluidic communication with at least one of said tanks so as to provide a continuous fluidic path from said vapor inlet to said condensate outlet through said plurality of tubes and said plurality of tanks. 
     
     
       6. A method for assembly of a condenser suitable for use in an automotive air conditioner or other refrigeration unit, comprising: providing a pair of spaced headers formed from an aluminum alloy brazing stock material wherein said aluminum alloy brazing stock material comprises an aluminum alloy core layer clad on both surfaces with an aluminum-silicon brazing alloy characterized by about 6.8 to about 14 weight percent silicon, each of said spaced headers having a corresponding plurality of perforations;   depositing a braze flux paste onto at least a first surface of each of said headers, said braze flux being deposited between each of said plurality of perforations in an amount sufficient to deoxidize and wet a region adjacent said perforations during a subsequent brazing operation, said braze flux paste comprising about 40 to about 60 weight percent potassium fluoaluminate particles dispersed in a liquid carrier, said liquid carrier consisting essentially of, by weight, from about 90 percent to 100 percent of propylene glycol and up to about 10 percent water;   inserting a tube into each of said corresponding perforations within each of said headers so as to extend in hydraulic parallel between said headers, such that each of said first surfaces of said headers having said braze flux is oppositely disposed across said extended plurality of tubes;   inserting high surface area, finned portions between each of said tubes; and   brazing said plurality of tubes within said perforations of said headers by heating to a temperature of about 1070° F. to about 1135° F. for a duration sufficient to melt said aluminum-silicon brazing alloy and said braze flux such that said braze flux deoxidizes said aluminum alloy core layer and said aluminum-silicon brazing alloy at said perforations while also enhancing the flowability of said aluminum-silicon brazing alloy, thereby being effective to form leak-proof brazed joints at said perforations so as to produce a leak-proof condenser suitable for use in a refrigeration system.   
     
     
       7. A method for assembly of a condenser as recited in claim 6 further comprising the steps of attaching each of said spaced headers to a corresponding extruded aluminum alloy tank means so as to form a plurality of tanks and attaching a vapor inlet and a condensate outlet such that each of said tubes is in fluidic communication with at least one of said tanks so as to provide a continuous fluidic path from said vapor inlet to said condensate outlet through said plurality of tubes and said plurality of tanks.